We propose to continue our studies of several iron proteins using Mossbauer spectroscopy and electron paramagnetic resonance. By combining both techniques it is possible to study the details of catalysis in considerable detail. Our studies will focus on a variety of dioxygenase enzymes and on a novel class of iron-sulfur centers. Specifically, we will study the following proteins: Non-heme iron dioxygenases cleave aromatic rings by oxygen insertion reactions. We propose to continue our investigations of extra- and intradiol cleaving enzymes and we will study proteins from the pseudomonas strains P. testosteroni, P. aeruginosa, P. arvilla C-l, and P. putida. In addition we will study the mammalian enzyme kidney 3-hydroxyanthranilate dioxygenase from beef kidney. We have recently given evidence for a new type of iron-sulfur cluster. We have found this center to be present in electron-transfer proteins and enzymes. We will study the new structure extensively in a ferredoxin from D. gigas and in aconitase from yeast and A. vinelandii.